Tone selective adjustment of images

Abstract

Methods, systems and apparatus, including computer program products, for processing an image. A first tone value is determined for a location within the image based upon attributes of pixels within a first neighborhood surrounding the location. The first tone value specifies a local weight for a first tone adjustment in the image. A second tone value is determined for the location based upon attributes of pixels within a second neighborhood surrounding the location. The second tone value specifies a local weight for a second tone adjustment in the image. The image is adjusted at the location using the first and second tone adjustments according to the local weights specified by the first and second tone values, respectively.

1. A method for processing an image, the method comprising:
 identifying one or more neighborhood size parameters, one or more tone function shape parameters, and one or more tone adjustment strength parameters; and 
 for each location of multiple locations within the image, performing tone selective adjustment, where performing tone selective adjustment comprises:
 determining a shadow neighborhood and a highlight neighborhood, each neighborhood comprising an area of the image surrounding the location that is based on at least one of the one or more neighborhood size parameters; 
 determining a shadow neighborhood intensity for the shadow neighborhood, the shadow neighborhood intensity being a measure of values of a local attribute specified by pixels within the shadow neighborhood; 
 determining a highlight neighborhood intensity for the highlight neighborhood, the highlight neighborhood intensity being a measure of values of a local attribute specified by pixels within the highlight neighborhood; 
 determining a shadow tone value representing a characterization of a shadow tone of the neighborhood, where the shadow tone value is based on the shadow neighborhood intensity and a shadow tone function, where the shadow tone function is based on at least one of the one or more tone function shape parameters; 
 determining a highlight tone value representing a characterization of a highlight tone of the neighborhood, where the highlight tone value is based on the highlight neighborhood intensity and a highlight tone function, where the highlight tone function is based on at least one of the one or more tone function shape parameters; 
 determining a shadow local weight for a shadow tone adjustment based on the shadow tone value and at least one of the one or more tone strength adjustment parameters; 
 determining a highlight local weight for a highlight tone adjustment based on the highlight tone value and at least one of the one or more tone strength adjustment parameters; 
 adjusting the image at the location using the shadow local weight for shadow tone adjustment and the highlight local weight for highlight tone adjustment. 
 
 
   
   
     2. The method of  claim 1 , wherein:
 for each pixel in each neighborhood, the value of the local attribute depends on luminosity of the pixel. 
 
   
   
     3. The method of  claim 1 , wherein:
 for each pixel in each neighborhood, the value of the local attribute depends on a maximum color value of the pixel. 
 
   
   
     4. The method of  claim 1 , wherein:
 for each pixel in each neighborhood, the value of the local attribute is a weighted average of a luminosity and a maximum color value of the pixel. 
 
   
   
     5. The method of  claim 1 , wherein:
 determining each neighborhood intensity comprises averaging the values of the local attribute for pixels within the corresponding neighborhood. 
 
   
   
     6. The method of  claim 5 , wherein:
 averaging the values of the local attribute for pixels within each neighborhood includes averaging the values of the local attribute according to gaussian weights that are assigned to each pixel in the neighborhood based upon a distance between the pixel and the location. 
 
   
   
     7. The method of  claim 5 , wherein:
 averaging the values of the local attribute for pixels within each neighborhood includes averaging the values of the local attribute according to weights that are assigned to each pixel in the neighborhood based upon a difference between the local attribute at the pixel and the location. 
 
   
   
     8. The method of  claim 1 , further comprising:
 receiving user input selecting a range of neighborhood intensity values for which the shadow or highlight tone value is substantially different from a reference value. 
 
   
   
     9. The method of  claim 1 , wherein:
 the tone function is a generic function or a general Gaussian function. 
 
   
   
     10. The method of  claim 1 , wherein:
 the shadow neighborhood and the highlight neighborhood are substantially identical. 
 
   
   
     11. The method of  claim 1 , further comprising:
 for each location of one or more of the multiple locations, performing the following operations:
 identifying a graphics object within the image, the location lying inside the graphics object; and 
 restricting the shadow and highlight neighborhoods for the location inside the graphics object. 
 
 
   
   
     12. The method of  claim 11 , wherein:
 identifying the graphics object includes identifying lines or edges in the image. 
 
   
   
     13. The method of  claim 1 , further comprising:
 determining one or more additional tone values for the location, each of the additional tone values specifying a local weight for a corresponding tone adjustment in the image; and 
 wherein adjusting the image at the location includes using each of the additional tone adjustments according to the corresponding tone value. 
 
   
   
     14. The method of  claim 13 , wherein:
 at least one of the additional tone values is determined based on the shadow and highlight tone values. 
 
   
   
     15. The method of  claim 1 , wherein the shadow and highlight tone adjustments are related to each other by a negative symmetry. 
   
   
     16. A system for image processing, the system comprising:
 a local adjustment tool to adjust an image including a plurality of pixels, the local adjustment tool including a shadow tone component and a highlight tone component, wherein:
 each of the shadow and highlight tone components is operable to determine a tone value and a corresponding local weight for adjustment for a location in the image by performing operations comprising:
 determining a neighborhood comprising an area of the image surrounding the location that is based on at least one of one or more neighborhood size parameters; 
 determining a neighborhood intensity, the neighborhood intensity being a measure of values of a local attribute specified by pixels within the neighborhood; 
 determining a tone value for the location, the tone value representing a characterization of a tone of the neighborhood, where the tone value is based on the neighborhood intensity and a tone function, where the tone function is based on at least one of one or more tone function shape parameters; and 
 determining a local weight for a tone adjustment based on the tone value and at least one of one or more tone strength adjustment parameters; 
 
 the local adjustment tool is operable to adjust the image at a location using the corresponding local weights determined by each of the shadow and highlight tone components according to the local weight specified by the corresponding tone value. 
 
 
   
   
     17. The system of  claim 16 , further comprising:
 an image capturing device to generate the image. 
 
   
   
     18. The system of  claim 17 , wherein the image capturing device includes a digital camera or a scanner. 
   
   
     19. The system of  claim 16 , further comprising:
 a display device to display the image. 
 
   
   
     20. The system of  claim 19 , wherein the display device is implemented in a portable device. 
   
   
     21. The system of  claim 16 , wherein at least one of the tone components specifies an adjustment parameter for the corresponding tone adjustment, the system further comprising:
 a user interface to set a value for the adjustment parameter. 
 
   
   
     22. A computer readable storage device storing a computer program of instructions which, when executed by a computer processing apparatus, cause the apparatus to perform a method for processing an image comprising:
 identifying one or more neighborhood size parameters, one or more tone function shape parameters, and one or more tone adjustment strength parameters; and 
 for each location of multiple locations within the image, performing tone selective adjustment, where performing tone selective adjustment comprises:
 determining a shadow neighborhood and a highlight neighborhood, each neighborhood comprising an area of the image surrounding the location that is based on at least one of the one or more neighborhood size parameters; 
 determining a shadow neighborhood intensity for the shadow neighborhood, the shadow neighborhood intensity being a measure of values of a local attribute specified by pixels within the shadow neighborhood; 
 determining a highlight neighborhood intensity for the highlight neighborhood, the highlight neighborhood intensity being a measure of values of a local attribute specified by pixels within the highlight neighborhood; 
 determining a shadow tone value representing a characterization of a shadow tone of the neighborhood, where the shadow tone value is based on the shadow neighborhood intensity and a shadow tone function, where the shadow tone function is based on at least one of the one or more tone function shape parameters; 
 determining a highlight tone value representing a characterization of a highlight tone of the neighborhood, where the highlight tone value is based on the highlight neighborhood intensity and a highlight tone function, where the highlight tone function is based on at least one of the one or more tone function shape parameters; 
 determining a shadow local weight for a shadow tone adjustment based on the shadow tone value and at least one of the one or more tone strength adjustment parameters; 
 determining a highlight local weight for a highlight tone adjustment based on the highlight tone value and at least one of the one or more tone strength adjustment parameters; 
 adjusting the image at the location using the shadow local weight for shadow tone adjustment and the highlight local weight for highlight tone adjustment. 
 
 
   
   
     23. The computer readable storage device of  claim 22 , wherein:
 for each pixel in each neighborhood, the value of the local attribute depends on luminosity of the pixel. 
 
   
   
     24. The computer readable storage device of  claim 22 , wherein:
 for each pixel in each neighborhood, the value of the local attribute depends on a maximum color value of the pixel. 
 
   
   
     25. The computer readable storage device of  claim 22 , wherein:
 for each pixel in each neighborhood, the value of the local attribute is a weighted average of a luminosity and a maximum color value of the pixel. 
 
   
   
     26. The computer readable storage device of  claim 22 , wherein:
 determining each neighborhood intensity comprises averaging the values of the local attribute for pixels within the corresponding neighborhood. 
 
   
   
     27. The computer readable storage device of  claim 26 , wherein:
 averaging the values of the local attribute for pixels within each neighborhood includes averaging the values of the local attribute according to gaussian weights that are assigned to each pixel in the neighborhood based upon a distance between the pixel and the location. 
 
   
   
     28. The computer readable storage device of  claim 26 , wherein:
 averaging the values of the local attribute for pixels within each neighborhood includes averaging the values of the local attribute according to weights that are assigned to each pixel in the neighborhood based upon a difference between the local attribute at the pixel and the location. 
 
   
   
     29. The computer readable storage device of  claim 22 , further comprising instructions operable to cause one or more data processing apparatus to perform operations comprising:
 receiving user input selecting a range of neighborhood intensity values for which the shadow or highlight tone value is substantially different from a reference value. 
 
   
   
     30. The computer readable storage device of  claim 22 , wherein:
 the tone function is a generic function or general Gaussian function. 
 
   
   
     31. The computer readable storage device of  claim 22 , wherein:
 the shadow neighborhood and the highlight neighborhood are substantially identical. 
 
   
   
     32. The computer readable storage device of  claim 22 , wherein the method further comprises:
 for each location of one or more of the multiple locations, performing the following operations:
 identifying a graphics object within the image, the location lying inside the graphics object; and 
 restricting the shadow and highlight neighborhoods for the location inside the graphics object. 
 
 
   
   
     33. The computer readable storage device of  claim 32 , wherein:
 identifying the graphics object includes identifying lines or edges in the image. 
 
   
   
     34. The computer readable storage device of  claim 22 , wherein the method further comprises:
 determining one or more additional tone values for the location, each of the additional tone values specifying a local weight for a corresponding tone adjustment in the image; and 
 wherein adjusting the image at the location includes using each of the additional tone adjustments according to the corresponding tone value. 
 
   
   
     35. The computer readable storage device of  claim 34 , wherein:
 at least one of the additional tone values is determined based on the shadow and highlight tone values. 
 
   
   
     36. The computer readable storage device of  claim 22 , wherein the shadow and highlight tone adjustments are related to each other by a negative symmetry. 
   
   
     37. The system of  claim 17 , wherein the image capturing device includes a CCD device. 
   
   
     38. The system of  claim 17 , wherein the local adjustment tool is configured to provide feedback to the image capturing device. 
   
   
     39. The system of  claim 38 , wherein the image capturing device is configured to locally adjust sensitivity based on the feedback to generate an adjusted image. 
   
   
     40. The system of  claim 20 , wherein the portable device includes a personal digital assistant, a mobile phone, or both. 
   
   
     41. The system of  claim 40 , wherein at least a portion of the local adjustment tool is implemented in a remote server. 
   
   
     42. The system of  claim 20 , wherein the local adjustment tool is implemented in the portable device.